From e53a4a8de2379f7a0d2e62c52ee40cd03f9cd9fc Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 16 Oct 2019 08:52:12 -0600
Subject: [PATCH] disallow constant folding of mutable field access

original commit: 7ac8cd69fc709200c1c0064f8031855a950ea8d3
---
 s/cp0.ss | 1 +
 1 file changed, 1 insertion(+)

diff --git a/s/cp0.ss b/s/cp0.ss
index d1729f5be4..c2319777b0 100644
--- a/s/cp0.ss
+++ b/s/cp0.ss
@@ -5004,6 +5004,7 @@
             (or (nanopass-case (Lsrc Expr) (result-exp e0)
                   [(quote ,d)
                    (and (record? d rtd)
+                        (not (csv7:record-field-mutable? rtd index))
                         (make-seq ctxt e0 `(quote ,((csv7:record-field-accessor rtd index) d))))]
                   [(record ,rtd1 ,rtd-expr ,e* ...)
                    (let loop ([e* e*] [re* '()] [index index])